


An Exercise in Mutual Understanding

by anachronist



Category: Fate/stay night & Related Fandoms, 文豪ストレイドッグス | Bungou Stray Dogs
Genre: Alternate Universe, Holy Grail War (Fate), M/M, Non-Linear Narrative, Sexual Content, please do not repost this fic on other sites
Language: English
Status: In-Progress
Published: 2019-05-31
Updated: 2019-06-12
Packaged: 2020-03-30 23:55:45
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 2,654
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19038160
Author URL: https://archiveofourown.org/users/anachronist/pseuds/anachronist
Summary: The life and times of Assassin, his renegade Master, and their destructive quest for the Grail





	1. Chapter 1

**Author's Note:**

> I swear this has a proper first meeting intro, but this was the bit that got finished first.
> 
> Ofc it had to be a part with smut

Mana transfers with Assassin, it seemed, were doomed to be exercises in patience. Unfortunately for the Servant in question, it was a quality Fyodor possessed in spades.

"Why, Master. I always knew you were a sadist. Good to know that nasty disposition of yours made it all the way to bed." Assassin paused in his examination of the handcuffs on his wrists to survey the man in bed with him. "It's to make up for your lack of stamina, isn't it?"

Instead of giving an immediate reply, Fyodor deliberately popped open the bottle cap and squeezed a liberal amount of lube on his palm.

"You'll find there are ways to work around anemia." He gave Assassin a meaningful look. "As do you with handcuffs."

Not that Assassin had any sleeves to pull out a convenient lockpick at this point in time. Being naked save for his bandages tended to do that, and his Master was ever so thorough in searching him. Still, Assassin laughed - all he had to do was revert back to his spirit form, and they both knew it.

It was such a _pity,_ really, that servants relied on receiving mana from their masters for strength. Truly a tragedy. To think that Assassin would tear himself apart choosing between this _torment_ and being left vulnerable on the battlefield, moreso when he had to burn through his energy to outmaneuver and win against their mutual opponents.

At the end of the day, freeing himself from the neverending cycle of the Throne was a bigger goal compared to these small trifles with Fyodor.

Still, the servant always delighted in being contrary out of petty spite.

"Do I, now." 

There was an edge in Assassin's smile that only sharpened when his Master nudged his things apart.

Fyodor fixed that by drizzling cool lube on Assassin's dick, making the man yelp.

"Ow, _fuck,_ Masterrrr!"

Assassin would've probably preferred to use a dictionary of insults and derogatory names. Fyodor's use of a command spell to keep his servant from calling him anything else was a good investment, not in the least because it prevented the little shit from revealing his name to others.

Indeed, it was a gift that kept on giving.

"Call my name, and I'll stop."

The ill-concealed flash of resentment and betrayal on Assassin's face was exquisite.


	2. Chapter 2

**Notes for the Chapter:**

> Now, for a semblance of actual plot.
> 
> Fair warning: all Nasu-isms will be used very loosely.

"Oh? Do I really have such a frail man as my Master?" Assassin looked amused as he walked around his summoner, footsteps echoing in the otherwise abandoned warehouse. "A gust of wind might topple you into a pit of knives, and we'd have lost the War."

How did someone disreputable such as himself end up in this kind of situation anyway? The dead were supposed to _stay dead,_ as he'd often fantasized about while he was still living. Instead, he was back to dreaming of a more permanent death in the middle of his miserable afterlife.

Well, it wasn't his first time in this era, even if his memories of the other grail wars were fuzzy. Assassin could always pay a visit to a certain academy and burn their history department just because, and his current master didn't seem the type to bat an eyelash at property damage and loss of life.

"Speaking from experience?" 

A question from his master, who cast a slow glance at the bandages covering every inch of his Servant's skin save for the face and hands. With how ill the former looked, anyone else would've thought he habitually minimized movement to avoid worsening his health condition.

Assassin suspected that wasn't the entire story.

He continued to circle his master at the same idle pace. After all, he was not under any obligation to confirm or deny it.

"Make no mistake: you summoned the worst Servant possible for direct combat." He gave his Master an unrepentant smile. Terrible first impressions had its uses, and Assassin could already tell that charming his way into this man's good graces wouldn't matter in the long run. "All the heavy lifting's on you and your thin, tooth-scarred malnourished fingers."

It wasn't as if Assassin's renown was substantial enough for him to have made a lasting mark in history. Apparently, someone thought otherwise.

His legend as people told it went something like this this: he and his fellow comrades risked life and limb to defend the country in secret during the turbulent Meiji period in Japan. Due to certain scandals and the political agendas of their opponents, however, they remained on the side of infamy until only a few years ago, when they were exonerated and granted posthumous honors after a fortunate historian unearthed evidence to clear the group's name. Among those uncovered artifacts was a collection of Assassin's old letters and drafts. Seeing the man's written thoughts had played a large role in restoring his image in the public's eyes.

Perhaps "fortunate" was a generous description for what actually happened. The reality was that the magecraft used to distort the evidence failed after the remaining magus from a minor family, one Oguri Mushitarou, was declared dead of old age, and no one thought to mention the fresh surgery wounds around his cranium in the autopsy report.

For weeks, the Church had been too busy sanitizing any press releases relating to both the murder and the historical finds. At such a hectic time, it was easy for a few uncatalogued items to be displaced in one storage room or another.

That was the easy part.

How a Russian freelancer, of all people, found out that he was also General Mori Ougai's mysterious Demon Protege was another matter entirely. In Assassin's lifetime, he had been informed that all the documents referencing his old deeds had been destroyed. Unless -

His gaze fell on the catalyst the man had used. 

_Ah._

Now he understood all too well, and it was only with the ease of practice that he kept a polite smile on his face.

A scrap of frayed black fabric with charred edges. Assassin knew just who in his lifetime would've kept that piece and decades' worth of regret.

His old friend ( _ex-friend_ , Assassin mentally amended, as his current self had yet to make peace with the man, and he didn't care what future him thought) was too meticulous to just have left this lying around even after his death. So something happened for this item to have a change of hands, and he doubt his new Master would shed light on the subject any time soon.

In fact, his new Master didn't look like the type to shed actual light on anything, regardless of his pristine. It was not only the catalyst that drew him here, but the faint impression he received of his summoner.

In that shell of a man dressed in white was another monster. As Assassin would discover much, much later, they were too alike when it came to the similarities they shared.

As for their differences...

"Only my thumbs," his master replied in a bland tone, though there was no mistaking the ease he carried himself with. This was the confidence of a man who planned his victories and succeeded. "And that isn't a problem."

Those were not responses typical of a magus.

Magi, especially aristocrats who inherited centuries' worth of wealth, tradition, and magical circuits, were a prideful group. Self-styled nobility that they were, they preferred to throw their weight and assert authority, treating Servants as nothing more than familiars. This wasn't much of an issue for heroic spirits from later eras who lived in a world where empires rose and fell, but for those who lived in the Age of the Gods? The magus was better off falling in line if they valued their life.

But he digressed.

"Then, by all means, work as hard as you like, even if it's to the ends of death and despair! Ah, but I must say - it's just as well that you didn't summon me as another class." In spite of his apparent cheer, Assassin's iries were the color of rust in the dim light. An ocean of of old, dried blood. "My older self would detest working with you."

A warning and acknowledgment, from one puppeteer to another. Assassin's future grief, the details of which were still lost to most save for a scant hint in his letters, was but a shadow of unrealized memory in his current form. Now, he was unable to dull the cruelty and arrogance of a youth that lived in his own nightmares and misery, though Assassin's physical manifestation was older than his actual age when he parted ways with General Mori.

The origins of myths were oddities. Even after his first disappearance, there were those who still thought the Demon Prodigy had plotted uprisings elsewhere, and a dozen other incidents he was not even around for had been attributed to that figure's name.

His Master looked unsurprised. If anything, the man was pleased, and his pale smile was both captivating and eerie in the night. "And the you of now does, too?"

 _What do you think,_ Assassin was tempted to say, which was definitely a yes. But -

"I'm sure we can come to an agreement." 

Assassin's smile was just as unpleasant as his Master's. 

After all, his bid for permanent oblivion was long overdue.

**Notes for the Chapter:**

> tl;dr - this is mafia!Dazai in a 20 y/o body working with Fyodor. Fun times.


	3. Chapter 3

His Master liked strong and bitter tea.

" _Bleagh!_ " Assassin scrunched his nose as he scraped his tongue with his sleeve. His own cup was half-full, a third of its contents swimming in the saucer. "You call that tar pit _tea!?_ I've tasted better moonshine than this!"

"You've no room to talk," Fyodor replied, casting a meaningful glance over his book at the tall glass next to Assassin: a monstrosity of decaf, milk, and too much sugar. "This is its traditional flavor. Japanese nationals prefer the clarity of taste, do they not?"

Implying that Assassin's palate was either unrefined or uncultured. Or both.

Good thing Assassin made it a point to avoid this kind of high-handed snootiness when he was alive, even if he was born into it.

"That's the farthest thing from clear!" To make a point, he stuck his finger in his teacup, to the silent disapproval of his Master. "Why, it's as black as a swamp. Or your soul! Perhaps that's why you drink it - my dear polite and well-mannered Master sips his tea from the finest of porcelain, only to betray his spite with its contents."

Ordinarily, Assassin would be in his spirit form when they were in public, surveying the area while his Master went about his business. It had been an enlightening tour of how Japan had changed in the past century or so, for seeing this post-modern world was different from merely knowing the theoretical knowledge gained from the Throne. It was an age of convenience Assassin would've liked to drift in, with so many things to busy himself with before his so-called untimely death.

As if the occurrence of death ever was part of some purpose other than the outcome of a sequence of events.

(In the back of his mind, he knew his older self had died of natural causes in old age, content. Assassin could never imagine it, and he stamped the thought out of his mind in an ugly fit of what he refused to recognize as jealousy.)

What people said of dying was the same then as it was now, something he found rather hilarious when he saw more aimless people walking on the streets.

Their current target was not part of that statistic: one Francis Scott Fitzgerald, Master of Foreigner, his own Master's former client of several hits and artifact retrievals. Just how far would a self-made man go to revive his wife and child when his wealth wasn't enough to cut it?

Perhaps Assassin would find out in this unusually public business meeting.

"Your Servant makes a good point, old sport."

Speak of the devil.

Master and Servant made a striking pair for all the wrong reasons: where Fitzgerald was immaculate and unabashedly arrogant, Foreigner, too dark and unnaturally tall, clearly didn't want to be in the sunlight. Or anywhere outside for that matter, judging from his gloomy discomfort as he looked around.

How strange, for a being who could easily crush the building and everyone in it, and whose class could reputedly overpower ridiculous Berserkers.

Still, Assassin was nothing but a seasoned negotiator, and he could take care of the niceties if his taciturn Master preferred to remain observing for now.

"Yo!" With a smile, Assassin gestured to the two other seats on the table. "Nice to see someone agrees with me. Coffee? Tea? As our guest, you're most welcome to order and break my Master's bank account."

Fitzgerald snorted and took his seat, waving for Foreigner to follow suit. "No need. We've had our fill, knowing your Master's inclination to poison people."

Assassin's smile widened, sharp at the edges. He could see why his Master, hopeful destroyer of Magi everywhere, tolerated this person whose size of ego rivalled his own.

"He has the nastiest hobbies," Assassin agreed, reaching for the syrup pot and adding a dollop or several to his tea. "Did you know that's why the Church keeps on trying to recruit him as Executor in spite of his un-Catholic background?"

"Assassin." That was his Master, closing his book.

"What?" Assassin innocently waved at Fitzgerald, who only looked wickedly amused. "It's not as if he hasn't guessed with his connections!"

"Old news," Fitzgerald generously allowed, and did not mention his Reverend friend.

"It is irrelevant," his Master said, bringing out the envelope tucked in his inner coat pocket and sliding it across the table. "Your terms."

Discussions like this were not usually public. Not in a town where the Church's representative had ways of knowing, nor at a spot Archer could easily see from a vantage point halfway across town.

Both these Masters were counting on it.

Fitzgerald picked up the missive after taking out an ivory-handled letter holder from his jacket pocket to break the wax seal.

"I see," he said after scanning the letter's contents. "The usual will be forwarded to the same."

His Master nodded and sipped his tea. Then, in what seemed like an abrupt change of topic, "What's your opinion on opera?"

"A good spectacle if the troupe is good." Fitzgerald tucked both envelope and letter opener in his pocket. "And I watch only the best."

"There's an ongoing performance in this city. The next show is seven this evening." His Master gave a thin smile. "I've heard their production is rather... riveting."

"Then it would be best for me to attend and see for myself." Fitzgerald's smile hardened, and Assassin saw the shrewd businessman underneath. "If it's not as good as promised, I'm ruining you and your associates."

"There won't be a need, I assure you." His Master remained at ease with sickly satisfaction. "When has my information failed you?"

"Information in and of itself is not predisposed to betrayal." _Unlike you,_ Fitzgerald didn't say.

Assassin laughed and clapped his hands.

In the morning, both Caster and Berserker would be dead, and Archer and their master would be close to broken.

"Safe travels to the opera," he told Fitzgerald with a casual tip of his teacup. What a smart man, Assassin would later think, cutting his losses once he got his prize from Caster's Master and leaving his old associate to be destroyed by that treacherous thing called the Grail.

Foreigner - _Lovecraft_ \- went with him. Their objective never had been winning this war. Those who strove towards their goals with the strength of will might use wishes, but never be beholden nor depend on them.

And when his Master later took him for a mana transfer after everything was said and done for the day, Assassin couldn't help but admire the fresh command seals streaking the man's arm, blood red on pale skin.

**Notes for the Chapter:**

> Let me know what you think!


End file.
